To add or subtract terms with exponents, both the base and the exponent must be the same. In this case they are so subtract the coefficients and retain the base and exponent:

-4b⁵ - 4b⁵
(-4 - 4)b⁵
-8b⁵

To subtract these radicals together their radicands must be the same:

9\( \sqrt{28} \) - 9\( \sqrt{7} \)
9\( \sqrt{4 \times 7} \) - 9\( \sqrt{7} \)
9\( \sqrt{2^2 \times 7} \) - 9\( \sqrt{7} \)
(9)(2)\( \sqrt{7} \) - 9\( \sqrt{7} \)
18\( \sqrt{7} \) - 9\( \sqrt{7} \)

Now that the radicands are identical, you can subtract them:

If 72% of the town's 50,000 voters cast ballots the number of votes cast is:

(\( \frac{72}{100} \)) x 50,000 = \( \frac{3,600,000}{100} \) = 36,000

The mayor got 65% of the votes cast which is:

(\( \frac{65}{100} \)) x 36,000 = \( \frac{2,340,000}{100} \) = 23,400 votes.

If the tiger has consumed 50 pounds of food in 5 days that's \( \frac{50}{5} \) = 10 pounds of food per day. The tiger needs to consume 100 - 50 = 50 more pounds of food to reach 100 pounds total. At 10 pounds of food per day that's \( \frac{50}{10} \) = 5 more days.

To find the average of these 4 numbers add them together then divide by 4:

\( \frac{12 + 10 + 13 + 9}{4} \) = \( \frac{44}{4} \) = 11